1. INTRODUCTION
Pollinators are important agents for a stable ecosystem (Kremer, 2008;
De Groot et al., 2010). They enhance pollination for both wild and
flowering plants and also help humans to increase agricultural
production (Kevan et al., 1990; Corbet et al., 1991; Widhiono et al.,
2016). These insects also benefit the economic, aesthetic, and cultural
aspects of mankind (Gill et al., 2016). In general, social and solitary
bees, butterflies and moths, beetle and flies account as dominant
pollinators (Vanbergen and Initiative, 2013; Wojcik, 2021).
Most of the cultivated plants around the world are pollinated by bees
(56.5%), flies (19%) and, butterflies (4%) (Bashir et al., 2019).
Honey bees are well–known insects in comparison to wild pollen bees
(Losey and Vaughan, 2006; Potts et al., 2010) while flies and
butterflies are less known. (Jennersten, 1984; Larson et al., 2001).
Pollinators decline is a globally recorded phenomenon (Carvalheiro et
al., 2013; Dirzo et al., 2016). Especially, bumblebees (Fitzpatrick et
al., 2007; Cameron et al., 2011), butterflies (Warren et al., 2001; Van
Swaay et al., 2010), and honeybees (Vanengelsdrop et al., 2008)
population is shrinking in the world due to natural as well
anthropogenic threats. The major drivers of pollinator loss are
recognized as habitat loss, landscape modification, intensification in
agriculture, and even climate change (Kearns et al., 1998; Potts et al.,
2010; Kovács‐Hostyánszk et al., 2017). Hence, maintaining pollinator
diversity in the given landscape requires an understanding of a clear
pattern of pollinator diversity along with the habitat types.
The community composition of pollinators depends upon the local
environment (Williams et al., 2010). The activity of pollinators is
strongly correlated with air temperature; bees and butterflies prefer
warmer temperatures than flies (Kühsel & Blüthgen, 2015), plant species
richness (Hudewenz et al., 2012), and elevation; Hymenoptera is dominant
pollinators in lowland while Lepidoptera and Diptera dominate at high
land (Warren et al., 1988). They require a range of habitats for
fulfilling their ecological requirements. However, these ecological
demands for insect pollinators are mostly species or guild–specific
(Proesmans et al., 2019). Bees prefer to forage the flower plants close
to the nesting area (Gathmann and Tscharntke, 2002; Greenleaf et al.,
2007). Hoverflies and butterflies do not construct the nest and fly away
from the egg–laying areas for foraging. Aphidophagous hoverflies such
as Episyrphus , Sphaerophoria depend on agricultural
habitat (Jauker et al., 2009; Pinheiro et al., 2015), while saproxylic
hoverflies (Xylota ) are benefitted from the forest (Reemer,
2005), hence, strongly associated with them. Butterflies forage
varieties of flower for nectar (Tiple et al., 2005) and can make the
flight over greater distances (Herrera, 1987). Such movement may show
the selection of varied nutrition of butterflies; pollen (Gilbert,
1972), tree sap, rotting fruit, and dung, decaying flesh, and dissolved
minerals in wet sand or dirt. Additionally, oviposition–plant location
signifies habitat selection for smaller and less mobile butterflies,
such as the ”blues,” while the larger butterflies like Erebia
epipsodea and Colias probably have fairly large ranges of the
search for their widespread ovipositing plants (Sharp et al., 1974).
Bee’s community structure is also designated by the availability of the
nesting substrates. Bee species construct the nest in deadwood (Sydenham
et al., 2016) and in the soil of sun–exposed ground (Everaars et al.,
2011). So, habitat sharing among the pollinators is obvious. The habitat
types play a crucial role in the community composition, abundance,
diversity, and species richness of flowering plants and hence the
pollinators.
Few studies were found on the study of insect pollinators in different
habitats of National Park. We hypothesized that the visit of insect
pollinators depends on the floral diversity found in the given habitats.
The presence of these plants is strongly influenced by habitat types and
elevation. The general understanding is that the natural habitat, if
free from pesticides, will probably possess more diversity than the
managed habitat. However, the habitat heterogeneity would also affect
the pollinator community as the interaction plant–pollinator is
specific (Weibull et al., 2000; Rundlöf et al., 2008; Oliver et al.,
2010).
Similarly, we examined species richness, abundance and, the community
composition of insect pollinators in different habitats along the
elevation gradient. The pollinator survey was carried at
Shivapuri–National Park (SNNP) including managed habitats of buffer
zone areas. The research questions were designed to find whether the
pollinator composition (richness, abundance, and their association)
differs from the defined habitats (grassland, managed area, open trails,
and trails of forest) of SNNP. ‘Is pollinator composition influenced by
the elevation gradient at the landscape?’